Hearing aid circuit with integrated switch and battery

ABSTRACT

A hearing aid includes a circuit board having a battery affixed thereon and a switch that utilizes a portion of the circuit board as a portion of the switch. The battery is permanently affixed to the circuit board in at least one location and at least a portion of the battery is spaced away from the circuit board. The circuit board further includes at least one pair of printed switch traces. The switch is integrated into the circuit board in a way that utilizes the circuit board to form a rotary switch.

RELATED APPLICATIONS

This application is related to a co-pending U.S. Utility applicationSer. No. 11/343,906, filed Jan. 30, 2006, entitled “Hearing Aid WithTuned Microphone Cavity,” in the name of Walter P. Sjursen, MichaelDeSalvo and Hassan A. Mohamed. This application is also related to aco-pending U.S. Design Patent No. 29/253,043, filed Jan. 30, 2006,entitled “Hearing Aid,” in the name of Walter P. Sjursen, MichaelDeSalvo and Hassan A. Mohamed, Paul J. Mulhauser and Karl D. Kirk, III.The entire teachings of the above applications are incorporated hereinby reference.

BACKGROUND OF THE INVENTION

A hearing aid, in general, comprises a housing or ear mold whichcontains a receiver, a microphone, electronic circuitry connecting thereceiver and the microphone, and a battery for operating the electroniccircuitry. The housing is an ear mold which fits into the ear canal ofthe user.

There has been a growing need for small, reliable, easy to use low-costhearing aids. In particular, it would be desirable to be able to providea hearing aid design that could meet the needs of the vast majority ofusers experiencing age related hearing loss. Individuals with agerelated hearing loss is the fastest growing segment of the hearingcompromised population. Still further, this aging population typicallyalso experiences some loss in fine motor skill and vision. This furtheraccentuates the need for hearing aids that have simple to use controls.A small and low cost hearing aid that is easy to use, comfortable, andmeets the hearing needs of the vast majority of this growing segment ofthe population could support mass production techniques that wouldfurther reduce product cost; another desirable characteristic for olderpeople who often have a limited income.

One problem facing hearing aid manufacturers is that the shape ofvarious ear canals are very complex. The cross-section of the smallestarea in the ear varies from a flat ellipse to a circle with a largenumber of sizes of each shape. This is further complicated by the factthat the ear canal bends up to 90 degrees in many ears. Standard hearingaids are custom fitted to each individual and constructed from a hardplastic which should fit the ear canal exactly. This custom fitting isan expensive and time-consuming process, which greatly increases thecost of the hearing aid, and because it is hard and durable it isgenerally uncomfortable.

Many attempts have been made in the art to provide small and easy to usehearing aid components and hearing aids. Still other prior art attemptshave focused on reducing the cost of hearing aids and to broaden theirappeal among the target population.

However, these attempts and others in the art suffer from severaldrawbacks. As illustrated by the plethora of attempts to improve ease ofuse and product cost, the prior art attempts do not provide hearing aidsthat are easy to use or low cost. Thus hearing aids of the art do notappeal to a large portion of potential users due to complexity and costcausing potential users to continue to suffer with uncorrected hearingloss or to use inferior partially out-of-the-ear product that areuncomfortable and unsightly.

Further, while hearing aids of the art have focused attention onminiaturization with ease of manufacture, neither of these objects haveyet been satisfied in the art. To fit the large variety of ear canalgeometries, hearing aids need to be even smaller.

What is needed in the art, therefore, is a hearing aid that is small yetlower in cost. One potential solution is to combine functions such as abattery door that also functions as a switch. While this may beefficient from a space/size perspective, it adds user and manufacturingcomplexity.

Thus, what is needed in the art is a hearing aid that is small and easyto operate, even with impaired dexterity and vision, while being lowerin cost and manufacturing complexity.

SUMMARY OF THE INVENTION

The present invention provides a hearing aid having a circuit boardcontaining a battery permanently affixed thereon wherein at least aportion of the battery is spaced away from the circuit board, and in oneembodiment, a vented cavity is formed between the battery and thecircuit board. The current invention further provides at least oneswitch trace on another portion of the circuit board, and in oneembodiment, a set of switch traces are integrated into a compact rotaryswitch that can be easily operated with a sliding motion of one finger.

A hearing aid includes a circuit board having a battery affixed thereonand a switch that utilizes a portion of the circuit board as a portionof the switch. The battery is permanently affixed to the circuit boardin at least one location and at least a portion of the battery is spacedaway from the circuit board. The circuit board further includes at leastone switch trace thereon. The switch is integrated into the circuitboard in a way that utilizes the circuit board to form a rotary switch.

According to one aspect of the invention, the space between the batteryand the circuit board forms a cavity. The cavity has a volume and aspacing from the battery cathode. The battery may be a metal-air typebattery. The cavity may have a vent through the circuit board and thecavity may be otherwise sealed. The vent may have precise geometry. Alaser may be used to form the vent.

According to another aspect of the invention, the battery is attached tothe circuit board by solder or by a conductive adhesive. The conductiveadhesive may be an epoxy adhesive. The circuit board may be a flexiblecircuit board (also known as a “flex circuit”). The battery anode mayfurther be attached to the flex circuit. At least a portion of themetal-air battery cathode surface may be concave in shape and have atleast one vent hole contained within the concave area. The circuit boardcan be attached to the surface of the battery having the concave area soas to provide spacing between the circuit board and the concave area ofthe battery, and to define a cavity between the battery and the circuitboard.

According to yet another aspect of the invention, the switch traces onthe circuit board are in the form of arcs. The arcs are concentric. Thearcs are contacted by a set of rotating electrical contacts. At somepositions of the rotation, the contacts close the circuit between twoswitch traces. In other positions, the contacts do not close the circuitbetween traces and thus the circuit is open. The circuit board withswitch traces and the rotating electrical contacts are used to form acompact rotary switch.

In yet another aspect of the invention, the circuit board containing theswitch traces also contains at least one vent. The vent is formed in thecircuit board during manufacture of the circuit board. A laser may beused to form the vent.

In yet another aspect of the invention, the switch traces may haveportions of higher electrical resistance and portions of lowerresistance.

In yet another aspect of the invention, a user-operable rotary switch isformed by having a tab extending out of the plane of rotation of theelectrical contacts. The user may move the tab over an arc causingdifferent electrical responses at different positions within the arc.The arc may be limited and may be perceived by the user as linear ratherthan rotary movements.

In yet another aspect of the invention, there may be more than one setof switch traces and there may be more than one rotating electricalcontact. The switch may have a means for maintaining a user-selectedposition. A spring may be used to keep the switch in a position. Afriction means may be used to keep the switch in a position. Theoperation of the switch may further block the vent to the cavity betweenthe circuit board and the battery when the switch is in an open circuitposition thereby limiting the cavity and the battery to just the airthey contain until the switch is reopened.

In another aspect, a hearing aid comprises a flexible circuit boardcontaining a battery permanently affixed thereto, the battery having afirst surface that is opposed to, and spaced away from, a surface of theflexible circuit board. The first surface of the battery can comprise atleast one air intake hole. The battery can be permanently affixed bysolder, an adhesive, or welding. The battery can be permanently affixedbattery to the flexible circuit board at the battery cathode. In certainembodiments, the battery and the flexible circuit board can form asubstantially enclosed chamber therebetween, and the chamber canincludes a reactant, such as oxygen, for reaction within the battery.The chamber can also include a vent to permit the reactant to enter thechamber, and the vent can be provided through the circuit board. Thehearing aid can also comprise a spacer between the surface of thebattery and the surface of the flexible circuit board, and the spacercan include an opening extending through the spacer, such that thesurface of the battery, the opposing surface of the circuit board andthe spacer form define the substantially enclosed chamber. The chambervent can be provided through the spacer.

In another embodiment, a hearing aid comprises a circuit boardcontaining a battery permanently affixed thereto, the circuit board andthe battery forming a substantially enclosed chamber.

In yet another embodiment, a hearing aid comprises a circuit board for ahearing aid comprising one or one switch traces. The switch trace orswitch traces can engage with at least one rotating electrical contactto form a rotary switch. The rotary switch can include a raised tab foruser operation, the raised tab extending from the plane of switchrotation. The raised tab can extend through a slot in the hearing aidface plate. In yet another embodiment, a flexible circuit boardcomprises at least one switch trace.

In yet another embodiment, a method of operating a hearing aid having acircuit and at least one switch trace comprises moving at least onerotating electrical contact relative to the at least one switch trace tomodify the operation of the hearing aid, such as turning the hearing aidon and off, adjusting the volume of the hearing aid receiver, or both.

In yet another embodiment, a hearing aid comprises a hearing aid shell;a microphone enclosed within the hearing aid shell; and a sealingmember, such as a gasket or o-ring, surrounding the periphery of themicrophone, and substantially completely filling the area between theperiphery of the microphone and the interior surface of the hearing aidshell. The microphone and sealing member can divide the interior volumeof the hearing aid shell into outer and interior volumes, andsubstantially acoustically seal sound waves in the outer volume of thehearing aid shell from entering the interior volume of the shell. Thehearing aid can further comprise a vent to vent air from the outervolume of the hearing aid shell to the interior volume of the shell,such that the vent can provide air to an air-activated battery locatedin the interior volume of the shell. The vent can comprise a slot in thehearing aid shell, or an air passageway through the sealing member. Thevent can be configured to substantially prevent sound waves in theaudible frequency range from entering the interior volume of the hearingaid shell.

In other aspects, the present invention relates to methods ofmanufacturing hearing aids as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention.

FIG. 1 illustrates a hearing aid.

FIG. 2 shows an exploded front view of the hearing aid of FIG. 1.

FIG. 3 shows an exploded rear view of the hearing aid of FIG. 1.

FIG. 4 shows an exploded view of a hearing aid electronics assembly.

FIG. 5 shows partially assembled hearing aid electronics assembly.

FIG. 6 shows a fully assembled hearing aid electronics assembly.

FIGS. 7A and 7B shows a hearing aid circuit board having switch traces.

FIG. 8 shows a hearing aid circuit board having a variable resistorswitch trace.

FIG. 9 is a front view of a hearing aid face plate with switchingmechanism.

FIG. 10 is a rear view of a hearing aid face plate with switchingmechanism.

FIG. 11 shows a hearing aid battery spaced apart from a circuit boardand forming an enclosure.

FIG. 12 is a cross-sectional front-view of a hearing aid microphone withsealing gasket.

FIG. 13 is a side cross-sectional view of the hearing aid microphone ofFIG. 12.

FIGS. 14A and 14B show a hearing aid face plate and a rotary switchhaving an air passageway through the switch.

FIGS. 15A, 15B and 15C show an alternative design for a hearing aidhaving a rotary switch in three different switch positions.

DETAILED DESCRIPTION OF THE INVENTION

A description of preferred embodiments of the invention follows.

A hearing aid is shown in FIG. 1 and is given generally as 10. Thehearing aid includes a hearing aid shell 28, that is generally made froma durable, rigid or semi-rigid material, such as a molded plastic, and ahearing aid tip 42 that is preferably comprised of a flexible, compliantmaterial to facilitate deep, comfortable fitting of the device in theear canal of a user. The tip 42 can include a mushroom shaped portion 44and a body portion 38. As shown in FIG. 1, the body portion 38 connectsto the hearing aid shell 28, and functions as a stem-like support forthe mushroom shaped portion 44, which extends radially out from thedistal end of the tip 42, so as to form an acoustical seal when thedevice is inserted in the user's ear canal. A sound port 40 extendsthrough tip 42 in order to convey amplified sound from the hearing aidinto the user's ear. The tip 42 can be formed of a rubber material, suchas silicone rubber. The tip 42 can also be cast in a mold using variousdurometer rubbers. A wax guard 43 can be attached to the tip 42 over thesound port 40 to trap and capture cerumen, and prevent the cerumen fromentering the sound port and clogging the receiver.

The various components of the hearing aid 10 are more clearlyillustrated in the exploded views of the device in FIGS. 2 and 3. As isshown in these figures, the hearing aid shell 28 is comprised of a pairof half-shells, 29 a and 29 b, which are joined together to form ahousing for a microphone 20, battery 30, flex circuit 34 and receiver36. The shell 28 is made to generally conform to the contours of the earcanal of a typical user. However, the shell 28 does not need to becustom designed to fit the ear of a specific user (like the ear molds ofconventional hearing devices), but is instead designed to comfortablyfit in the ear of a relatively large percentage of the generalpopulation. Preferably, the present invention is a one-size-fits-all, orat least a one-size-fits-most device. It can also be a uni-ear device,meaning that the device can be worn in either the right ear or the leftear. The flexible tip 42 attaches to the distal end of the shell 28,proximate to the receiver 36. A face plate 18 attaches to the twohalf-shells at the proximal end of the device to complete the hearingaid enclosure. The face plate 18 preferably includes a pull-tab 37 tofacilitate insertion and removal of the device from the user's ear. Theface plate 18 in this embodiment also includes one or more openings 39to permit air and sounds to enter the hearing aid shell. Located behindthe face plate 18, and partially protruding from the face plate is arotary switch 19. Together, the face plate 18 and rotary switch 19function as a switching mechanism 21 for the hearing aid, the details ofwhich will be described below.

As shown in FIGS. 2 and 3, the interior of the hearing aid 10 comprisesa microphone 20, a battery 30, a circuit board 34, and a receiver 36, aswell as associated circuitry and electrical connections. In a preferredembodiment, the circuitry and electrical connections are located on aflex circuit 34, that wraps around the various components of the hearingaid to act as the internal wiring and electrical contacts for thehearing aid, and can also contain the signal processing circuitry forthe hearing aid. An embodiment of a flex circuit 34 and associatedhearing aid components is shown in exploded view in FIG. 4. As shown inFIG. 4, the flex circuit 34 comprises several different portions: aswitch trace portion 45, a microphone mating portion 46, a receivermating portion 48, and battery contacts 47, 49.

Although the hearing aid in this embodiment includes a single flexcircuit that contains the hearing aid circuitry and all of theelectrical connections between the various components of the device, itwill be understood that alternative designs are also possible. Forexample, the flex circuit 34 shown in this embodiment could besubstituted, in whole or in part, by other types of circuitry, such as anon-flexible circuit board, and various other types of electricalconnections, such as soldering and wire-connections, could be used.

An advantage of the present hearing aid using a flex circuit 34 is thatsubstantially all of the hearing aid circuitry and electricalconnections can be integrated onto a single component, and the variousinterior components of the hearing aid, such as the microphone 20,battery 30, and receiver 36, can be easily attached to the flex circuit34 to produce a fully functional hearing aid electronics module 11. Themodule 11 can then be inserted into the hearing aid shell 28 and the tip42 applied to provide a finished hearing aid. The hearing aid is thusextremely easy to manufacture on a large scale. This is illustrated inFIGS. 4-6, which shows the sequence of steps for the production of afully functional hearing aid module 11. As shown in FIG. 4, themicrophone 20 is aligned over the microphone mating portion 46, and thereceiver 36 is aligned over the receiver mating portion 48. The battery30 is generally mounted underneath the microphone mating portion 46 ofthe flex circuit 34, opposite the microphone 20. In a preferredembodiment, the cathode 31 of the battery 30 is mounted adjacent to andparallel with the microphone mating portion 46 of the flex circuit 34,but does not directly contact the flex circuit. As will be discussed indetail below, a gap is maintained between the battery surface and thesurface of the flex circuit opposite the microphone. In this embodiment,the gap is maintained by battery spacer 62.

FIG. 5 shows the flex circuit 34 with the microphone 20, battery 30 andreceiver 36 mounted to the circuit. The microphone 20 is mounteddirectly to a first surface of the flex circuit 34. The microphone 20 iselectrically coupled to the circuit such that the electrical signalsproduced by the microphone in response to external audio inputs can beprocessed by the circuitry on the flex circuit to provide a desiredfrequency response. The processed signal is then sent via electricalconnections in the flex circuit to the receiver 36, which is mounted onthe flex circuit at the receiver mounting portion 48 of the circuit. Thebattery 30 is mounted on the underside of the flex circuit, and isspaced from the flex circuit by battery spacer 62. A stiffener plate 64can be mounted on the flex circuit at the switch trace portion 45 of theflex circuit.

FIG. 6 illustrates the fully assembled hearing aid electronics module11. As shown in this figure, the switch trace portion 45 of the circuitis folded over the front surface of the microphone 20. The batterycontacts 47, 49 are folded over and brought into electrical contact withthe positive and negative terminals of the battery 30. The batterycontacts 47, 49 of the flex circuit can be substantially permanentlyattached to the battery 30 using solder or a conductive epoxy. Thecontacts could also be welded to the battery. (In this embodiment, thehearing aid is a disposable hearing aid, since the substantiallypermanently attached battery 30 is not intended to be replaced. Once thebattery is discharged, the hearing aid can be disposed of and replacedwith a new hearing aid. Alternatively, the battery could be arechargeable battery, and the battery can be recharged.) The receivermounting portion 48 is folded over so that the receiver 36 is locatedadjacent to the anode 33 of the battery 30. The fully assembled hearingaid electronics module 11 is a relatively small and compact assembly,which helps reduce the overall size of the hearing aid. The electronicsmodule 11 can be pre-assembled, and a plurality of these modules can bemass-produced, prior to the full assembly of the hearing aid devices.

Switching Mechanism

Turning now to one aspect of the invention, in certain embodiments thehearing aid circuit board comprises at least one switch trace thereon,and the hearing aid comprises a switching mechanism to allow a user toturn the hearing aid on or off, and/or to modify the volume of thehearing aid, and/or to otherwise effect the hearing aid's performance.FIG. 7A shows the switch trace portion 45 of the hearing aid flexcircuit 34 according to one embodiment of the invention. In thisembodiment, a pair of switch traces 61 are integrated with the hearingaid circuit board 34 to form an ON/OFF switch for the hearing aid. Asshown in FIG. 7A, the switch trace portion 45 of the circuit is mountedto the face of microphone 20, and includes a central opening to permitsound waves to reach the microphone. Surrounding this opening is a setof switch traces 61, made from an electrically conductive material thatis preferably printed on the circuit. The pair of switch traces 61 areelectrically connected to the hearing aid battery 30 such that theyrepresent a discontinuity between the battery 30 and at least onecomponent of the hearing aid, such that unless the discontinuity isbridged, the hearing aid 10 or a component thereof does not draw powerfrom the battery 30. Placement of a conductor material across the pairof switch traces 61 allows power to flow uninterrupted through thehearing aid components. As illustrated in FIG. 7A, when a conductivematerial is placed in position P1, the discontinuity across the set ofswitch traces 61 is not bridged, and the hearing aid, or at least one ormore components of the hearing aid, does not draw any power. The hearingaid can thus be considered in the “OFF” state when the conductivematerial is in position P1. However, when a conductive material isplaced in position P2, the discontinuity is bridged between therespective traces comprising trace pair 61. The hearing aid draws poweracross trace pair 71, and is now considered in the “ON” state. It willbe understood that the pair of switch traces 61 could be located in anypractical location on the circuit board. For example, they could beadjacent to one another on one side of the sound hole for microphone 20(as is shown in FIG. 7B, below).

In the embodiment shown in FIG. 7B, two pairs of switch traces 71, 73are provided on the switch trace portion 45 of the flex circuit, andconfigured to provide both an “ON/OFF” switch, as well as avolume-control function for the hearing aid. In this embodiment, switchtrace pair 71 comprises the “ON/OFF” switch, and the traces are locatedadjacent to one another on a first side of the microphone sound hole. (Asecond pair of switch traces 73 is located on the opposite side of thesound hole). When a conductive material is placed in position P1, thediscontinuity across the switch traces 71 is not bridged, and thehearing aid can thus be considered in the “OFF” state. However, when aconductive material is placed in position P2, the discontinuity isbridged between the respective traces comprising trace pair 71. Thehearing aid draws power across trace pair 71, and is now considered inthe “ON” state.

FIG. 7B also illustrates an example of a volume control mechanism for ahearing aid. In this embodiment, when a conductive material is placed inposition P2, the electrical resistance of trace pair 71 determines theamount of power drawn, and this can be used to control the volume ofreceiver 36. For example, when the conductive material is in positionP2, the hearing aid is “ON,” at “LOW” volume. When the conductivematerial is placed in position P3, the conductive material bridges bothtrace pairs 71 and 73. The resistance across the traces is now altered(for example, bridging the second set of traces can short out avolume-limiting resistor), and the hearing aid is now “ON” at “HIGH”volume. Various modifications to this basic volume control mechanismwill be readily understood. In general, the switch traces on the circuitboard are configured such that the physical position of a switch contactacross the traces determines two or more resistance values across thetraces, where the respective resistance values across the traces controlthe volume of the hearing aid.

As shown herein, the switch traces are preferably in the form of arcs,though they could be straight or have any useful configuration. In oneembodiment, the trace width is at least about 0.1 mm. In yet anotherembodiment, the trace width is at least about 0.3 mm. In yet anotherembodiment, the trace width is at least about 0.5 mm. In anotherembodiment, the trace width is less than about 5 mm. In yet anotherembodiment, the trace width is less than about 3 mm. In yet anotherembodiment, the trace width is less than about 2 mm. Each trace isgenerally between about 0.1 and 5 mm in width, and preferably have aspacing between adjacent traces of between about 0.5 and 2 mm. In oneembodiment, the spacing between adjacent tracings is at least about 0.5mm. In yet another embodiment, the spacing between adjacent traces is atleast about 0.8 mm. In another embodiment, the spacing between adjacenttraces is less than about 2 mm. In yet another embodiment, the spacingbetween adjacent traces is less than about 1.5 mm. Where the switchtraces are in the form of arcs, they generally have a radius of fromabout 1 mm to about 6 mm, and preferably from about 2 mm to about 5 mm.The switch traces can comprise copper, for example. The switch tracescan also be plated with other metals. In one embodiment, the switchtraces comprise copper that is nickel plated, and then further platedwith gold. The nickel prevents the gold and copper from diffusing intoeach other, and the gold plating provides a reliable switch contactsurface.

Although the embodiment shown here comprises two pairs of switch traces,it will be understood that the switching mechanism could comprise asingle pair of switch traces, or just one switch trace, such that thehearing aid, or a component of the hearing aid, draws no power until aconductor material is placed in contact with at least one switch trace.It will be understood that more than two pairs of switch traces couldalso be employed.

It will be understood that various modifications to this basic switchtrace scheme can be employed to provide varying levels of resistance,and thus varying hearing aid performance states. For example, as shownin FIG. 8, an alternative configuration of switch traces is shown, inwhich there is only a single pair of switch traces 81, 83. In thisembodiment, one of the traces 81 comprises a variable resistor. Thus, asthe conductive bridge material is moved from position P1 (“OFF”), to P2,P3 and P4, the electrical resistance across the traces is altered (from1000Ω to 750Ω to ˜0Ω, respectively). The trace 81 is electricallyconnected to receiver 36, thus providing essentially continuous volumecontrol for the receiver across a particular dynamic range. It will beunderstood that the maximum resistance across the traces may be higheror lower than 1000Ω, and the resistance may be made to vary linearly ornon-linearly with the physical position of a switch contact. In general,the maximum resistance value across the traces is from about 1000 to10,000Ω, with a preferred maximum value of about 2000 to 4000Ω. It willalso be understood that the resistance across the switch traces need notbe in series with the receiver, but could instead by connected to thesignal processing circuitry in order to accomplish a volume controlfunction, or another function such as a tone control function. If theresistance is connected to the signal processing circuitry, the maximumresistance value can be even higher, such as 100 kΩ, or even 1 MΩ.

An exemplary embodiment of a switching mechanism 21 according to theinvention is shown in FIGS. 9 and 10. FIG. 9 is a front perspective viewof the face plate 18 and rotary switch 19 of the hearing aid. FIG. 10 isa rear perspective view of the face plate 18 and rotary switch 19. Aspreviously discussed, the rotary switch 19 is located directly behindthe face plate 18 in the hearing aid. As shown in FIG. 10, the rotaryswitch 19 generally has a smaller diameter than the face plate 18, andcan rotate in a plane (in the direction indicated by arrow) relative tothe face plate. The rotary switch may have a hollow shaft 76 and araised tab 78 that extend out of the plane of rotation of the rotaryswitch 19. The hollow shaft 76 is located substantially at the axis ofrotation of the rotary switch 19, and the raised tab 78 is radiallyoffset from the shaft 76. The hollow shaft 76 can comprise one or moreholes extending therethrough to permit air and sound waves to enter thehearing aid. The face plate 18 contains a pair of openings 77, 79,including a central circular opening 77 through which the hollow shaft76 extends, and an arc-shaped slot 79 through which the raised tab 78extends. The rotary switch 19 is thus rotatable with respect to the faceplate 18 over a limited angular range by moving the raised tab 78 withinthe arc-shaped slot 79. In general, the radius of rotation of the raisedtab 78 is between about 2.5 mm and about 5.0 mm, and the arc of rotationof the tab is less than about 100 degrees, and generally between about20 degrees and 70 degrees. In one embodiment, the radius of rotation ofthe raised tab 78 is at least about 2.5 mm. In yet another embodiment,the radius of rotation of the raised tab 78 is at least about 3 mm. Inanother embodiment, the radius of rotation of the raised tab 78 is lessthan about 5 mm. In yet another embodiment, the radius of rotation ofthe raised tab 78 is less than about 4 mm. In one embodiment, the arc ofrotation of the tab is less than about 80 degrees. In yet anotherembodiment, the arc of rotation of the tab is less than about 70degrees. In another embodiment, the arc of rotation of the tab is atleast about 20 degrees. In yet another embodiment, the arc of rotationof the tab is at least about 40 degrees.

While not wishing to be bound by theory, it is believed that the rotaryswitch of the present invention is easy to operate, even for those withimpaired dexterity, because the movement from one switch location to thenext approximates a straight-line movement. Preferably, a switchsegment, that is the rotation from one position to the next position,should not be greater than about 50 degrees. More preferably, a switchsegment is not greater than about 40 degrees. Even more preferably, aswitch segment is not greater than about 35 degrees. On the other hand,a switch segment movement should be sufficient that the user realizesthat movement has occurred. Preferably, a switch segment should be atleast about 5 degrees; more preferably, at least about 7 degrees; andeven more preferably, at least about 8 degrees.

On the bottom surface of the rotary switch 19 are one or more rotatingelectrical contacts 75. These contacts are configured to selectivelyengage with the switch traces on the hearing aid circuit to serve as theconductive “bridge” across the switch traces, as described in detailabove. Thus, by moving the raised tab 78 the protrudes through the faceplate of the hearing aid, the user is able to selectively bring therotating electrical contacts into and out of engagement with the one ormore switch traces on the hearing aid circuit. In general, the user isable to at least switch the hearing aid between and “OFF” state and an“ON” state, and is typically also able to move the switch to control thevolume of the hearing aid, in the manner described above in connectionwith FIGS. 7A, 7B and 8. In the embodiment shown in FIGS. 9 and 10, forexample, the user can move the switch into one of three positions,corresponding to three different operating states for the hearing aid:“OFF,” “Low Volume,” and “High Volume.” The rotating electrical contacts75 of FIG. 10 can be rotated to bridge pairs of adjacent switch traceson the circuit board, such as shown in FIG. 7B, for example.

Generally, the switch mechanism 21 includes tactile means to permit theuser to easily determine the position of the raised tab 78 within slot79, and thus the position or operating state of the electrical contacts75 with the switch traces 71, 73. The switch mechanism preferably alsoincludes means for maintaining the switch in a desired operating stateuntil changed by the user. For example, in FIG. 10, the face plate 19contains a pattern of notches 84 along its inner circumference that matewith a detent 85 on the rotary switch 19 over a series of discreteswitch locations corresponding to discrete operating states of thehearing aid. As the user moves the switch to different positions, themovement of the detent 85 to an adjacent notch 84 enables the user toknow that the operating state of the device has changed. Alternatively,a similar series of notches could be provided on the arc-shaped slot 79of the face plate 18. Also, visual means could be provided to enable theuser to determine the position of the switch, such as markings on theface plate or rotary switch, or a color-coded pattern on the rotaryswitch that is visible as the user rotates the raised tab to variouspositions.

An advantage of the rotary switching mechanism is that the switchprovides the added functionality of an ON/OFF switch and/or volumecontrol for a hearing aid while adding essentially no additional bulk tothe hearing aid, since virtually the entire switching mechanism operatesin the plane of the hearing aid face plate. Moreover, the rotary switchis very easy to use, since the raised tab rotates over a relativelylimited arc, and thus approximates the operation of a linear switch.

In yet another embodiment, the rotary switch 19 can be employed tocontrol air flow to the interior of the hearing aid, including air flowto the hearing aid battery. This is illustrated in FIGS. 14A and 14B,which depict a front view of the hearing aid face plate 18 with rotaryswitch 19. As shown in FIG. 14A, the raised tab 78 of the rotary switch19 is at a first switch position within arc-shaped slot 79. An air hole301 (shown in phantom) is provided through the rotary switch 19. In thisswitch position, the air hole 301 is covered by the face plate 18, andthus ambient air cannot enter the hearing aid through air hole 301. Asealing mechanism between the air hole 301 on the rotary switch 19 andthe interior surface of the face plate 18 can be employed to furtherrestrict air from entering the hearing aid. In FIG. 14B, the raised tab78 is moved to a second switch position, which exposes the air hole 301to ambient air. Air can thus enter the hearing aid through air hole 301.Preferably, air is not permitted to enter through air hole 301 whenrotary switch 19 is in a power off position. Air hole 301 can comprisean air passageway to the hearing aid battery, a sound passageway to thehearing aid microphone, or both. Air hole 301 can comprise the primarymeans for air and/or sound to enter hearing aid, or it can supplementadditional openings for air and sound.

A hearing aid having a switching mechanism and a selectively-sealableair hole 301 is illustrated in FIGS. 15A, 15B and 15C. These figuresdepict a hearing aid that is similar to the hearing aid of FIG. 1. InFIG. 15A, the user-operable tab 78 of the switching mechanism is shownin a first switch state. This corresponds to the “OFF” operating stateof the hearing aid. The air hole 301 through the rotary switch 19 is notvisible in this switch position. In FIG. 15B, the tab 78 is shown in asecond switch state, which corresponds to the “LOW volume” operatingstate of the hearing aid. Note that with the movement of the tab 78 fromthe first (OFF) state to the second (LOW volume) state, the air hole 301of the rotary switch 19 is now rotated into alignment with thearc-shaped slot 79 of the face plate 18, and is exposed to ambient air.Finally, FIG. 15C depicts the tab 78 in a third switch state, whichcorresponds to the “HIGH volume” operating state of the hearing aid. Theair hole 301 through the rotary switch 19 remains exposed through thearc-shaped slot 79 of the face plate 18 in this switch state. It shouldalso be noted that FIGS. 15A-15C illustrate one example of visualindicators 303, 305, 307 on the hearing aid which help the userdetermine the switch position and operating state of the hearing aid.Indicator 303, which in this example is a solid dot, indicates that thehearing aid is OFF. Indicator 305, which comprises a single bar,indicates that the hearing aid is on LOW volume. Indicator 307, whichcomprises a pair of bars, indicates that the hearing aid is on HIGHvolume. These indicators can be color-coded to further helpdifferentiate the operating states. For example, the “OFF” indicator canbe red, while the “ON” indicator(s) can be green.

Battery/Circuit Gap and Air Flow Restriction

Turning now to FIG. 11, the interface of the hearing aid battery 30 andthe hearing aid circuit 34 is shown in cross-section. As discussedpreviously, in one aspect of the invention, the hearing aid battery 30is mounted behind the microphone mating portion 46 of the flex circuit34, opposite the microphone 20 (shown in phantom). The surface of thebattery 30 generally extends adjacent and parallel to the flex circuit34, but does not contact the flex circuit at this interface. In certainembodiments of the invention, a gap 101 is formed and maintained betweenthe battery surface and the opposing surface of the flex circuit. Onesignificant advantage of maintaining this gap is that the risk of ashort circuit forming between the battery and a conductive element ofthe flex circuit, such as solder bumps 103 (or any other electricalcomponents) extending from the underside of the circuit, is greatlyminimized.

The gap 101 between the battery and the flex circuit can be formed andmaintained using any desired means. In the embodiments illustrated here,the gap 101 is maintained by battery spacer 62, as was previouslydescribed in connection with FIGS. 4-6. The spacer is preferably madefrom an electrically insulating material to prevent short circuitingbetween the battery and the flex circuit. In yet another embodiment, thespacer may have at least one electrically conductive portion that may beused to establish an electrical connection between the battery and thecircuit board.

In certain embodiments, the hearing aid battery 30 comprises anair-activated power source, such as a metal-air (e.g. zinc-air) battery.These batteries use oxygen as a reactant. As such, the hearing aid mustbe designed so that a sufficient quantity of air reaches the air accesshole(s) on the cathode side of the battery. It would be desirable tocontrol the flow of air (or any similar battery reactant) to the batteryin order to minimize the impact of environmental conditions on theperformance of the battery (e.g., to prevent the battery from drying outor flooding).

In yet another aspect of the present invention, the hearing aid circuit34 forms a substantially air-tight seal with at least one portion of thebattery 30 in order to control air flow to the battery. Preferably, thecircuit 34 and the battery 30 form a substantially enclosed chambertherebetween, where the chamber comprises a vent 105 to control the flowof a reactant (e.g. air) to the battery. In one embodiment, the chamberhas an interior volume of at least about 0.01 mm³. In yet anotherembodiment, the chamber has an interior volume of at least about 0.05mm³. In yet another embodiment, the chamber has an interior volume of atleast about 0.1 mm³. In yet another embodiment, the chamber has aninterior volume of at least about 0.15 mm³. In yet another embodiment,the chamber has an interior volume of at least about 0.2 mm³. In yetanother embodiment, the chamber has an interior volume of at least about0.25 mm³. In another embodiment, the chamber has an interior volume ofless than about 25 mm³. In yet another embodiment, the chamber has aninterior volume of less than about 100 mm³. In yet another embodiment,the chamber has an interior volume of less than about 200 mm³. In yetanother embodiment, the chamber has an interior volume of less thanabout 300 mm³. In another embodiment, the chamber has an interior volumeof less than about 400 mm³. In another embodiment, the chamber has aninterior volume of less than about 450 mm³. Preferably, the chamber hasan interior volume from about 0.25 mm³ to about 25 mm³, and generallyfrom about 0.15 mm³ to about 450 mm³.

The vent 105 can be a hole through the circuit board, as shown in FIG.11. In one embodiment, the vent has a cross-section area of at leastabout 3×10⁻⁴ mm². In yet another embodiment, the vent has across-section area of at least about 6×10⁻⁴ mm². In yet anotherembodiment, the vent has a cross-section area of at least about 8×10⁻⁴mm². In yet another embodiment, the vent has a cross-section area of atleast about 1×10⁻³ mm². In another embodiment, the vent has across-section area of less than about 2×10⁻¹ mm². In yet anotherembodiment, the vent has a cross-section area of less than about1.5×10⁻¹ mm². In yet another embodiment, the vent has a cross-sectionarea of less than about 1×10⁻¹ mm². In yet another embodiment, the venthas a cross-section area of less than about 5×10⁻² mm². In yet anotherembodiment, the vent has a cross-section area of less than about 1×10⁻²mm². Generally, the vent hole 105 has a cross-section area of from about3×10⁻⁴ mm² to about 2×10⁻¹ mm², and preferably from about 1×10⁻³ mm² toabout 1×10⁻² mm². The vent hole 105 can be provided during manufactureof the circuit, and can by formed by a laser, a chemical etch process,mechanical drilling, or any suitable means. The vent hole may be round,multi-sided, symmetrical, non-symmetrical, regular, irregular or anysuitable shape.

As illustrated in FIG. 11 (and also shown in FIGS. 4-6), a spacer 62 canbe provided between the surface of the battery 30 and the surface of thecircuit board 34. The spacer 62 includes an opening extending throughthe surface of the spacer, and forms part of the substantially enclosedchamber. The surface of the battery comprises at least one air intakehole 107 that is at least partially open to the chamber. In general, thecross-sectional area of the vent hole 105 through the circuit issubstantially less than the cross-sectional area of the air intake hole107 in the battery. The effect of this is that the vent hole in thecircuit board acts as an air flow restrictor, restricting the flow ofair into the battery cathode. At the same time, the cross-sectional areaof the opening in the spacer 62 is generally substantially greater thanthe cross-sectional areas of both the vent hole in the circuit and theair intake hole in the battery, so that the vent hole 105 does not needto be closely aligned and registered with the battery's intake hole 107.

This is more clearly illustrated in the air flow patterns shown in FIG.11. As can be seen in the figure, ambient air is present in the gapbetween the hearing aid circuit board 34 and the microphone 20 (sincethe interface between these components is generally not air-tight). Asmall amount of this air enters the chamber between the circuit and thebattery through the small vent hole 105 in the circuit board.Significantly, the flow of air into this chamber can be controlled byselecting an appropriate size for the vent hole in the circuit board.Once the air enters the chamber, the chamber acts as an air reservoirfor the battery cathode. The size of this reservoir can be controlled byselecting an appropriate volume for the chamber. This volume can beselected to optimize the performance of the air-activated battery.Notably, in this embodiment, the vent hole 105 and the air intake hole107 of the battery are not aligned with one another, but because bothare open to the chamber, the air can still reach the battery through therelatively small vent hole 105. This is significant, since the locationof the air intake holes in metal-air batteries is not a standardizedfeature and can vary between manufacturers and models. Using the presentinvention, however, the circuit board with a vent hole 105 can stillprovide air to different types of metal air batteries, since precisealignment of the holes is not required. The fact that the vent hole 105acts as an air flow restrictor is an important factor for improvinghearing aid performance, since the restricted air flow to the batteryminimizes the risk of premature drying of the battery, excessive currentdraw, and other problems.

It will be further understood that although vent 105 is shown as anopening through the circuit board 34, the venting of the chamber 101could also be accomplished by providing a vent through the spacer 62.The vent could comprise, for example, a hole through the spacer, or agroove or slot on a surface of the spacer that allows air from thehearing aid housing to enter the substantially enclosed chamber 101. Thespacer itself could be made from an air permeable material in order toprovide a controlled air flow to the battery.

It will be understood that the battery spacer 62 is not required for theinvention, and at least a portion of the battery may be brought intodirect sealing engagement with at least a portion of the flex circuit,though this may require closer alignment between the vent hole 105 andthe air intake hole 107 of the battery. For example, in certainembodiments, the battery can include a depressed surface, so that arelatively sizeable chamber is formed between the depressed surface ofthe battery and the (generally flat) surface of the circuit board.

Sealed Microphone Cavity

Turning now to FIGS. 12 and 13, yet another aspect of the invention isillustrated. FIG. 12 shows a cross-section of a hearing aid according toone embodiment of the invention. As shown in this figure, the hearingaid microphone 20 is located within the hearing aid shell 28. A sealingmember 203, such as a gasket or o-ring, concentrically surrounds theperiphery of the microphone 20, and substantially completely fills thearea of the hearing aid between the outer periphery of the microphoneand the interior surface of the hearing aid shell 28. The sealing member203 surrounding the microphone 20 is shown in the side view of FIG. 13.An air vent 201 is provided to allow air to pass behind the sealingmember 203 to the interior portion 206 of the hearing aid housing, whichincludes the battery 30. In the embodiment illustrated in FIG. 12, theair vent 201 comprises a slot that is molded into the interior of thehearing aid shell 28. In this embodiment, the slot is about 8-mils wideand about 12-mils deep. Other shapes and sizes for the vent could alsobe used. In addition, multiple vents could be employed. The vent couldalso comprise a passageway through the sealing member 203. For example,as shown in FIG. 13, a hollow tube 207 (such as a hypodermic needle)could be inserted through the sealing member 203 to provide a ventpassageway. In addition, the sealing member 203 itself could comprise anair-permeable material to provide the venting of air to the interior ofthe hearing aid.

Preferably, the sealing member and vent arrangement provide an acousticseal, so that audible sound waves are substantially prevented fromentering the interior portion 206 of the hearing aid housing, while asufficient quantity of air is able to pass through the air vent 201 toprovide the necessary oxygen for the battery. In essence, the air ventis configured to provide a relatively high-impedance to audio frequencysound waves, but a relatively low impedance to the diffusion of oxygento the battery. Said another way, the vent represents a low impedance tovery low frequency signals including dc (direct current). The sealingmember and vent arrangement are thus air permeable, but substantiallyimpermeable to sound waves in the audible frequencies.

An advantage of this design is that the acoustical sealing provided bythe sealing member 203 eliminates the interior portion 206 of thehearing aid shell as a resonance volume that could distort the audiosignal received at the microphone. In addition, the presence of thesealing member 203 surrounding the microphone further reduces the volumeof the resonant cavity 205 in front of the microphone 205. This has theeffect of raising the resonant frequency of the cavity, and amplifyingthe high-frequency sound waves before they are received at themicrophone. The geometry of the cavity in front of the microphone can betuned to affect hearing aid audio performance, as is further describedin co-pending U.S. patent application Ser. No. 11/343,906, filed Jan.30, 2006, entitled “Hearing Aid with Tuned Cavity,” the entire teachingsof which are incorporated herein by reference. In addition, the venthole 201 acts as an air flow restrictor to the battery, similar to thevent in the circuit board described in connection with FIG. 11 above,and thus reduces the risk of premature drying of the battery, excessivecurrent draw, and other problems.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

1. A hearing aid comprising: a flexible circuit board containing abattery permanently affixed thereto, the battery having a first surfacecomprising at least one air intake hole the first surface opposed to,and spaced away from, a surface of the flexible circuit board; and aspacer between the surface of the battery and the surface of theflexible circuit board, the spacer having an opening extending throughthe spacer, such that the surface of the battery, the opposing surfaceof the flexible circuit board and the spacer form a substantiallyenclosed chamber, the at least one air intake hole on the first surfaceof the battery at least partially open to the enclosed chamber, theenclosed chamber having a vent through the flexible circuit board topermit air to enter the enclosed chamber, the cross-sectional area ofthe vent substantially less than the cross-sectional area of the airintake hole in the battery such that the vent restricts the flow of airto the air intake hole.
 2. The hearing aid of claim 1 wherein saidpermanently affixed battery is affixed by at least one of solder, anadhesive, and welding.
 3. The hearing aid of claim 1 wherein saidpermanently affixed battery is affixed to the flexible circuit board atthe battery cathode.
 4. The hearing aid of claim 1 wherein saidpermanently affixed battery is spaced away from said flexible circuitboard from about 0.005 mm to about 10 mm.
 5. A hearing aid comprising: aflexible circuit board containing a battery permanently affixed thereto,the battery having a first surface comprising at least one air intakehole, the first surface opposed to, and spaced away from, a surface ofthe flexible circuit board, the permanently affixed battery and theflexible circuit board forming a substantially enclosed chambertherebetween, the chamber having a vent through the flexible circuitboard, the cross-sectional area of the vent substantially less than thecross-sectional area of the air intake hole in the battery such that thevent restricts the flow of air to the air intake hole.
 6. The hearingaid of claim 5, wherein the chamber includes a reactant for reactionwithin the battery.
 7. The hearing aid of claim 5, wherein the batterycomprises an at least partially depressed surface, the flexible circuitboard being affixed to the battery surface to form said chamber.
 8. Thehearing aid of claim 5 wherein said chamber has an interior volume fromabout 0.01 mm³ to about 450 mm³.
 9. The hearing aid of claim 5 whereinsaid vent has a cross-section area of from about 3×10⁻⁴ mm² to about2×10⁻¹ mm².
 10. The hearing aid of claim 1 wherein said battery is ametal-air battery.
 11. The hearing aid of claim 1, wherein thecross-sectional area of the spacer opening is substantially greater thanthe cross-sectional area of the vent through the circuit board and thecross-sectional area of the air intake hole in the battery.
 12. Thehearing aid of claim 1, wherein the spacer comprises an insulatingmaterial.
 13. A hearing aid comprising: a circuit board containing abattery permanently affixed thereto, the circuit board and the batteryforming a substantially enclosed chamber, a surface of the batteryhaving an air intake hole that is at least partially open to thechamber, the chamber having a vent through the circuit board to permitair to enter the chamber, the cross-sectional area of the vent throughthe circuit board substantially less than the cross-sectional area ofthe air intake hole in the battery such that the vent hole restricts theflow of air to the battery intake hole.
 14. The hearing aid of claim 13,wherein the chamber includes a reactant for reaction within the battery.15. The hearing aid of claim 14, wherein the battery comprises ametal-air battery, and the reactant comprises oxygen.
 16. The hearingaid of claim 13, wherein the battery comprises an at least partiallydepressed surface, the circuit board being affixed to the batterysurface to form said chamber.
 17. The hearing aid of claim 13 whereinsaid chamber has an interior volume from about 0.01 mm³ to about 450mm³.
 18. The hearing aid of claim 13 wherein said vent has across-section area of from about 3×10⁻⁴ mm² to about 2×10⁻¹ mm².
 19. Thehearing aid of claim 13 wherein the circuit board is a flexible circuitboard.
 20. The hearing aid of claim 13, further comprising a spacerbetween the surface of the battery and a surface of the circuit board.21. The hearing aid of claim 20, wherein the spacer comprises an openingextending through the spacer, such that the surface of the battery, theopposing surface of the circuit board and the spacer form thesubstantially enclosed chamber.
 22. The hearing aid of claim 21, whereinthe cross-sectional area of the spacer opening is substantially greaterthan the cross-sectional area of the vent through the circuit board andthe cross-sectional area of the air intake hole in the battery.
 23. Thehearing aid of claim 20, wherein the spacer comprises an insulatingmaterial.